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Topic: JB3 Power (Read 4021 times)

Here is the first post. I am on vacation and am not done, but I figured it would need to be posted in pieces anyway. Might as well get up what I have done and modify later. Here you go.

This thread is intended to answer a few questions about powering the increasingly popular Nomad Jukebox 3 in the field for taping. There are four options I will discuss. I stole a lot of this info from the JB3 power thread, hopefully no hard feelings. I give credit for this information to all of those hard working tapers that contributed to the original 24-page thread.

But first some general questions about JB3 power draw. Q) How much power does my JB3 really draw?A) Although this is a subject of quite a bit of debate it seems that the JB3 draws about 1.2A during initial spin up and 260 mA with peaks of 800 or so on disc writes. For battery life calculations you can consider it to be around 600 mA (which conveniently fits the almost 3 hour battery life of the internal).

Q) Would a 4.8V 4000mah not work? Is the .2V that much missing as not to power it??A) 4.8v battery fully charged puts out low-mid 5s voltage. To use this method you have to run down the batteries somehow to get it to an acceptable voltage for the JB3. More on this in power option 2.

Alright that’s all the questions that I can think of for right now so lets get into the various powering options.

Power Option 1: Internal batts- Two fully charged internal JB3 batteries should give you about 6 hours of record time. Plan on five and a half to be safe, if your batteries are older maybe you should plan on less. The batteries cannot be charged outside the JB3…why we do not know…as Beaner once said. “If they only had an external charger, they be MONEY!!!” For most shows you should be good to go, but you are paranoid about internals or you have a festival to attend we must choose to move on to the next 3 powering options.

Power Option 2: External NIMH batteries- The second method is four rechargeable double A cells wired in sequence to create a 4.8 volt pack. The main problem with this method is the inability to power up your JB3 with the batteries fully charged. The reason for this, as stated earlier, is that NIMH batteries do not have a very constant output voltage. At first these four batteries will but out somewhere between 5.0 and 5.4 volts as measured with a voltimeter. So we are forced to run down the batteries before using them in the JB3. The most popular of method of discharging the batteries is to run them down in a flashlight or with a halogen light. The risk of this is getting various amount of discharge then not knowing how much runtime you actually have when you get out in the field. Therefore when running powering option 2 you need to make sure that your internals are fully charged. This way you can go for lets say three hours (this is considered the standard for four AA cells) on the externals. MAKE SURE the externals do not completely run out. YOUR JB3 WILL LOCK UP. But sometime within your three-hour period remove the external power from the JB3 and viola 3 or 6 hours more record time depending on how many internal batteries you have.

Q) So what do I need to use power option 2?A) 4-AA battery holder with lead wires 4 2100mAh 1.2 V niMH AA rechargeables a type B adaptaplug an adaptacableSolder the lead wires from the 4-AA battery holder onto the adaptacable make sure you know which lead is positive and which lead is negative coming out of the batt holder. Once the cable is soldered place the type B adaptaplug on the cable so that the tip will be positive it seems in most cases?? (there is a considerable amount of confusion arising from not having a constitant tip polarity). From there run down your batts after a full charge and enjoy. Just make sure your internals are fully charged so that you can unplug (its safer to do this during a break in the recording).

Power Option 3: Many of you are familiar with this option from running your UA-5s and various other toys via RC car batts. Here we are using a RC car battery and running a voltage regulator inline to get the voltage down to the JB3’s 5 volts. ---------------------------------More to come!---------------------------------------------

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I thought I'd add this info here, too. I just picked up a Powerrunner PR2310 li-ion battery, and it works great out of the box for powering the JB3. Original message is posted below. In it, I mention run-times. These were calculated based on power consumption draw of the JB3 at 300mA for recording, which was posted in a more recent thread than the above posting which assumes a 600mA draw. I have no idea which is right, but if the JB3 draw is more like 600ma, then the runtimes I listed below should be cut in half. Either way, the Powerrunner appears to be a good method of providing external power to the JB3. If it were me, I would remove the internal batteries when using the external powerrunner (or any external battery). That way, you do not use the external battery to charge the internal batteries.

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Well, not as nice as using internal batteries, but I just got a powerrunner li-ion external battery, at the doorstep when I returned from DC yesterday. I got it here:

Switchable output voltage of 3, 4.5, 5, 6, 7.5, and 12. Works like a charm with the JB3 at the 5v setting, right out of the box. No mods necessary, no buying extra parts or adapters or adaptaplugs. Really a very easy power solution to the JB3. At the 5v setting, it has a 7.2A-hr capacity, which given the power draw of the JB3, should be enough to run it for 24 hours. Or stated otherwise, the equivalent of 8 internal JB3 batteries, which would cost apparently about $400 if you could find them. The model I got, PR2310, was $70 from the above link. The same vendor has the PR2200 model which is the same physical size, but has half the capacity, for $50. This should run the JB3 for about 12 hours, or the equivalent of 4 JB3 batteries ($200).

I'm testing my battery out right now, running my JB3 without its internal batteries. Seems to be working great, booted up fine and I'm recording at 44.1k wav seemingly fine. I'll check the recording file in a bit, but I imagine it is all fine. I doubt I'll have the motivation to test exactly how long this will run, since it will probably be at least 20hours and more like 24.

I need to dig up the other thread, but I thought someone else tried this product and said it didn't work. I'm guessing he didn't have access to a voltmeter. The one issue I did find is the cable that comes with it is labelled wrong, so according to the actual labeling on the cable you'd have to run it with the adaptaplug in the "tip-negative" position in order to get it to have +5v at the tip (which is really "tip-positive"). I discovered this right away with my voltmeter before I ran it into the JB3. So besides this mis-labeling on the cable (no idea if this extends to the other ones they sell, but I imagine), it works fine, you just need to insure you've got it set up to provide +5v at the center tip of the cable (hence access to a voltmeter is handy).

Anyway, nothing against Marc's VR box, but to me it is easier just to have one battery, not a battery and a voltage regulator box (unless you're trying to run two pieces of equipment off the same battery setup). Bottom line, the Powerrunner is an excellent option for out-of-the-box JB3 powering, allowing long runtimes at little cost.

Note: The powerrunner is also available from the vendor off ebay at their actual website, though for a bit more:

thanks todd! once we see if the opti input can be fixed, i'll pick one of these uP!

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just got my powwer runner tday!! we'ss see how it holds up for Big summer classic on sunday...

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